1. Field of the Invention
The subject invention relates to cooling assemblies such as heat sinks for dissipating heat energy generated by electronic or non-electronic components.
2. Description of Related Art
Intense research is in progress to develop cooling assemblies or heat sinks for the electronics industry that are capable of efficiently dissipating heat from electronic and non-electronic components. Cooling of high heat flux components, such as chips, calls for the design of very efficient thermal management systems.
Examples of prior art cooling assemblies designed for cooling the high heat flux electronic components are shown in U.S. Pat. Nos. 5,508,884 and 6,082,443. These assemblies include a boiling section and a condensing section defining a chamber therebetween. Typically, the condensing section has a plurality of fins disposed on an external surface thereof. The heat generating component is connected to the internal or external surface of the boiling section. A working fluid, such as a halocarbon fluid, is disposed within the chamber. The captive working fluid changes from liquid-to-vapor in the boiling section as the working fluid absorbs heat from the heat generating component. Reverse transformation of the working fluid from vapor-to-liquid occurs as the working fluid rejects heat to a cooling fluid, such as air, flowing on the finned external surface of the condensing section. In particular, the vapor transforms to liquid once the vapor hits the condensing section. These prior art assemblies rely exclusively on gravity for the motion of the working fluid between the boiling and condensing sections. In particular, small droplets of liquid form on the condensing section and then drip through the vapor cloud. A fluid moving device, such as an axial fan, is typically disposed near the external surface of the condensing section to provide the necessary air flow across the condensing section.
All of the known prior art cooling assemblies include rectangular chambers with more or less equal surface area for both boiling and condensing. The heat generating components produce highly concentrated areas of heat such that it would be desirable that the boiling area be less than the condensing area and that the working fluid be concentrated in the areas of high heat flux. Another shortcoming of the rectangular chambers of the prior art cooling assemblies is that these chambers require a relatively large inventory of working fluid. In addition, the process of having the re-condensed liquid drip through the vapor cloud is undesirable as the efficiency of the evaporation process suffers. Further, the relatively large rectangular boiling sections can deflect or bow outwardly as the pressure within the chamber increases. This undesirable deflection of the boiling section can cause delamination of the heat generating component from the boiling section.